A reliable and inexpensive noninvasive procedure for detecting coronary stenosis would be highly useful in the diagnosis and in following the treatment of coronary artery disease. Biotronics has previously developed a phonoangiographic spectral analyzer (PSA) which is capable of measuring low frequency sound generated by arterial narrowing which produces post stenotic turbulence. Previous application of the PSA emphasized detection of stenosis was demonstrated at a local medical complex in comparison with Digital Subtractive Angiography and was approved for market entry by the U.S. Food and Drug Administration. The proposed Phase I SBIR research would extend the application of the PSA to detecting and measuring stenosis in the coronary arteries. This application is more difficult because of the interference of the first and second heart sounds and other background noise. This interference can be minimized, however, by proper timing of PSA measurement during diastole when coronary stenotic sounds are loudest and background sounds are at a minimum. Sophisticated signal processing and pattern recognition techniques will be used to extract signal and provide an accurate screen-level diagnosis. This is a revised application that responds to the criticisms in the previous summary statement. Both experimental data and literature are cited to demonstrate the potential feasibility of the proposed research.